Thursday, August 30, 2018
I cut open a Kanza nut today and captured the kernel filling process in progress. The first thing I noticed when slicing the nut in half is that the shell was completely hard. In the photo above, the arrow marked "S" points to the shell. At this point in time, the outer shell of the nut is fully formed and light tan in color.
The arrow marked "K" points to newly formed pecan kernel. The white creamy color is what we expect pecan kernel to look like. However, inside the white kernel layer is a translucent layer I've marked "J". This is rapidly forming kernel tissue that has yet to fully differentiate into its final solid white state. The translucent appearance of this not-yet-fully-formed kernel tissue is the origin of the term "gel stage".
When I first started working with pecans I was given the impression that kernel development progressed from water stage, to gel stage, to firm kernel. It was almost like the water turns to gel then solidifies into kernel. This is not how it works.
New kernel tissue develops starting from just under the pecan seed coat. As new kernel tissue develops, the water inside the nut is absorbed back into the tree. The amount of "gel" that can be seen inside the nut is dependent on the speed of kernel formation. The rate of kernel deposition is influenced by weather conditions and cultivar. This is the most "gel" I've ever found inside a Kanza nut. In past years, the gel layer was much thinner.
Kernel deposition is not the only pecan tissue I've seen with this translucent appearance. Back during grafting season, I noticed several stock trees with a layer adjacent to the cambium that had a water soaked or gel type look. This was obviously new wood tissue being formed that hadn't fully solidified.
Now when I think about pecan kernel development, I think of it in two stages. The first is "ovule expansion". Ovule expansion occurs during the first half of the growing season as pecan fruit grow rapidly in size. The culmination of this stage occurs when the nut achieves its full size and the inside of the nut is filled with water. The second stage is "kernel deposition". Kernel begins to develop on the inside of the seed coat and works it way towards the center. Kernel deposition continues until the shuck starts separating from the shell (shuck split).
Tuesday, August 21, 2018
I'll need to wait to see how things go during the last part of August and early September before deciding whether or not to make a second weevil spray in a few weeks.
Monday, August 20, 2018
As a young tree, Hark is easier to train than Kanza. Hark seems to have a more naturally spreading growth habit and produces fewer stalked buds than Kanza. As you know, stalked buds grow into narrow-angled branches that are prone to wind breakage. Although Kanza is not a terribly hard tree to train, I do need to keep a close look out for stalked buds during the early years of tree development.
With plenty of moisture available to fill out kernels, I'll be anxious to compare the nut quality of Kanza and Hark this coming Fall.
Thursday, August 9, 2018
Wednesday, August 8, 2018
At this point in the growing season, my Kanza nuts are approaching full water stage. It is too early for weevils to lay eggs but both stink bug and weevil feeding can cause serious nut drop. With our below average nut set this year, I definitely want to prevent any potential nut loss.
A couple more notes on spraying. I like to spray early in the morning. The high humidity and calm winds at that time of day helps the sprayer deliver the pesticide to the entire canopy. Since I'm using a late model tractor to spray the grove, I have a digital reading of ground speed. With my 12 speed tractor, I drive in 3rd gear and average 1.9 miles per hour. I operate the fan at full throttle.
Thursday, August 2, 2018
When the calendar turns to August, I immediately think about controlling pecan weevils. If the soil contains enough moisture, male weevils will start emerging in late July. By early August, females will appear. Both sexes migrate to pecan nut clusters in the hopes of finding a suitable mate (photo above).
During this courtship phase, male and female weevils will feed on nuts causing nuts, that are still in the water stage, to drop from the tree. Female weevils will continue to probe nuts until the pecan kernel inside the nut starts to firm up. Once a female finds solid kernel they will lay 5-7 eggs inside the nut. Our job, as pecan growers, is to prevent females weevils from laying eggs.
In my orchard, the weevil population is very low so I'm not overly anxious to start spraying for weevil. However, I am planning to spray for stinkbugs next week and that spray should take care of any early emerging weevil adults. My biggest concern is that fact the my neighbors native pecan grove doesn't appear to have a crop this year. That means, any weevils that emerge across the fence will probably migrate over to my orchard.
From past experience, migrating weevils are not captured in trunk mounted traps. So this year, I'll be making a weevil spray as soon as my Kanza nuts enter the dough stage in an effort to stop migrating weevils from becoming established in my orchard.
If you want to monitor pecan weevil emergence in your grove, I'd suggest that you build some Circle pecan weevil traps. Step by step instructions for building traps can be found HERE.